Anchors are used to fix each facing slab exactly in a predetermined position relative to a wall to be faced. In previous practice, anchors consisting of straight metal bolts, which were optionally twisted or profiled to increase their stiffness, were embedded in mortar in the wall to an appropriate depth, which was so selected that the associated slab was mounted in proper alignment. When the slabs are to be fixed quickly, delays should be avoided so that the anchors should be fixed as quickly as possible. This requires either the use of a rapid-setting cement mortar, which is expensive, or of additional metal pins, which are driven to support the anchor. For this reason the setting of the known anchors is rather time-consuming and complicated and requires either an expensive mortar or additional fastening means.